Removing Winter insulation and unblock roof ventilation

[user 6228]

Are you saying that the open mesh floor should be open all year? Seems like that would create a massive draft even with the roof vents etc closed.

They do cause massive drafts that bees have to use their bodies to divert.

 

[ericbeaumont]

Seems like that would create a massive draft

OMFs became all the rage during the 90s when it was suggested that the mesh would lose about 10 or 20% of varroa through grooming by bees.

Evidence to support the idea is thin on the ground but suppliers seized on the OMF as an opportunity to diversify a product.

More recently, US research in 2020 indicated that OMFs did result in lower varroa populations.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7564001/
However, it has also been shown that higher hive temps & humidity restrict varroa reproduction, in which case solid floors & top insulation would offer the better environment.

https://royalsocietypublishing.org/doi/10.1098/rsif.2019.0048
When deciding which floor & hive to choose, consider which matches more closely a natural nest, likely a hollow tree: small entrance, low thermal conductance, sealed roof.

When bees propolise mesh floors or vented roofs it is because they know best how to modulate the nest for optimum efficiency, and we really ought to heed their research.

 

[Poly Hive]

The OMF was never developed to counter varroa as the longer time served members should know. I've posted this times. Mobus did the research at Craibstone and published in the ABJ. The OMF was developed to improve wintering and was coupled with top insulation which was proven to improve winter losses, or rather to reduce the losses and improve wintering success.

PH

 

[Mabee]

As a beginner I have read and read the arguments for and against OMF vs Solid and am no wiser... I inherited OMF's and the advice from a retired beek to place an empty super on the stand then an OMF, to mitigate the effect of any random gusts during winter storms, that seems logical to me. I was wondering if an OMF then empty super then another OMF would help further dampen any gusts?
I also have 50mm Kingsland in the roof and all roof vents blocked.
What do you think?
K

Mine are mostly in a very exposed windy site, they do fine overwintering with omf and top insulation (all poly), the only other thing i’d recommend adding is an underfloor entrance which they all have, that encloses the bottom and prevents the worst weather getting in.
Like your profile pic btw, i’ve got 2 borders!

 

[Murox]

Mine are mostly in a very exposed windy site, they do fine overwintering with omf and top insulation (all poly), the only other thing i’d recommend adding is an underfloor entrance which they all have, that encloses the bottom and prevents the worst weather getting in.
Like your profile pic btw, i’ve got 2 borders!

Likewise here, exposed and windy. Also UFE, with poly and top insulation. A couple of hives are on swienty floors and I just keep the little slide in/out tray in most of the time and have blocked/reduced the integral entrance right down to around 100mm in length now.

 

[ericbeaumont]

OMF was never developed to counter varroa

Yes, I believe it goes way back to the 1930s, but nonetheless was hijacked and promoted as a tool of integrated pest management when varroa arrived.

 

[jenkinsbrynmair]

Yes, I believe it goes way back to the 1930

Michael Palmer photographed one on display out in Ireland which was being used in the first decade of the last century - I think he shared it on here.